This application is based on and claims priority from provisional application Serial No. 60/242,785, filed Oct. 24, 2000.
This invention relates to an automatic knot-tying machine, otherwise referred to in this application as a xe2x80x9cpackage knotter.xe2x80x9d One application for the machine is for use in various textile or other strand producing processes, hereinafter referred to as xe2x80x9ctextilexe2x80x9d processes. The invention is specifically intended to tie a slip knot in a single strand. Many textile machines, for example, spinning frames, winders and the like employ automated machines to tie two yarn ends together. This often happens when supply packages are exchanged. In effect, tying the two ends together permits the process to continue as if the yarn were a single continuous strand instead of two end-to-end strands connected together with a knot. As is apparent, the principal criteria for such a knot-tying machine is to quickly tie a knot which will not come untied and which is sufficiently strong to withstand the various stresses and tensions placed on the yarn during downstream processing.
This invention is distinctly different from machines and processes which tie together yarns or other strand material (xe2x80x9cyarnxe2x80x9d) end-to-end. Rather, a slip-knot is tied in the single free end of yarn on, for example, the outer surface of a wound package of yarn. The purpose of the knot is to prevent the package from beginning to unwind during doffing, transportation, storage and donning onto downstream machines. The slip-knot is easily untied simply by pulling the free end of the yarn.
Most prior art ways of preventing yarn from unwinding from a package involve using a short length of tape to adhere the free end to the outer surface of the package, or catching the yarn in a notch or slit in the end of the tube on which the yarn is wound.
In another prior art method, the free end of yarn is doubled and then forced through the edge of the outer surface of yarn by a long needle, so that some of the outermost wraps of yarn hold the doubled length of yarn in place. The end is freed by pulling on the free end. This process presents the possibility of damage to the yarn by the needle or tangling of the doubled yarn, particularly if it is pushed too far into the package.
Therefore, it is an object of the invention to provide a knot-tying machine which ties an easily-removable slip-knot in a strand.
It is another object of the invention to provide a knot-tying machine which ties an easily-removable slip-knot in a yarn end.
It is another object of the invention to provide a knot-tying machine which ties an easily-removable slip-knot in a yarn end on a textile yarn package.
It is another object of the invention to provide a knot-tying machine which automatically ties an easily-removable slip-knot in a yarn end on a textile yarn package as an integral function of a yarn package doffing step.
It is another object of the invention to provide a knot-tying machine which automatically ties an easily-removable slip-knot in a yarn end on a textile yarn package as an integral function of a yarn package doffing step, wherein the free end of the knotted yarn is always located in the same position across the width of the yarn package.
It is another object of the invention to provide a knot-tying machine which ties an easily-removable slip-knot in a yarn end on a textile yarn package, wherein the free end is adapted to be grasped and pulled to release the knot manually or automatically.
It is another object of the invention to provide a knot-tying machine which includes means for retaining an entire case of yarn packages at a processing machine and sending the entire case of yarn to the packing station at the same time.
It is another object of the invention to provide a knot-tying machine for use in combination with a textile winding machine, wherein multiple packages of yarn are doffed at the same time, conveyed one at a time to a knot-tying machine where a slip knot is tied in the yarn end of the yarn on the package.
It is another object of the invention to provide a knot-tying machine for use in combination with a textile winding machine or any other machine, wherein multiple packages of yarn are doffed at the same time or in any sequence and conveyed one at a time to a knot-tying machine where a slip knot in the yarn end of the yarn on the package, and further wherein a label is then automatically inserted into the package.
It is another object of the invention to provide a knot-tying machine which doffs an entire winder at the same time and then conveys the packages to a knot-tying station where the yarn end of each package is tied one at a time.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a knot-tying machine, comprising a package support for holding a package having a supply of a strand material with an exposed free end wound onto an outer surface of the package, a strand gripper for releasably gripping and holding a length of the strand adjacent the exposed free end of the strand, a loop-forming assembly for forming a loop in the length of the strand adjacent the exposed free end of the strand and intermediate the gripper and the package, the package support and the loop-forming assembly mounted for rotational movement relative to each other for forming the loop in the strand, and a knot-forming assembly for forming a slip-knot in the loop of the strand formed by the loop-forming assembly adjacent the free end thereof, the slip-knot being adapted to be subsequently removed when desired by pulling on the free end of the strand.
According to one preferred embodiment of the invention, the package support is stationarily mounted and the loop-forming assembly is mounted for rotation around the periphery of the package support for capturing the length of the strand adjacent the exposed free end of the strand for forming a loop therein.
According to another preferred embodiment of the invention, the loop-forming assembly is stationarily mounted, the package support is mounted for rotation about an axis which is stationary relative to the loop-forming assembly, the gripper is mounted concentrically with the package support for rotation therewith, the knot-forming assembly is mounted for rotation relative to the loop formed by the loop-forming assembly for inserting the knot in the loop.
According to yet another preferred embodiment of the invention, the loop-forming assembly includes an elongate member movable between a retracted position, an extended position within the loop formed by the loop-forming assembly, and a secondary loop-forming position wherein the elongate member is mounted on a pivot for rotation to form a secondary loop in the loop. Further, the knot-forming assembly includes a strand capture assembly carried by the elongate member for capturing a length of the strand between the loop and the gripper and pulling the length of strand through the secondary loop to form the slip knot.
According to yet another preferred embodiment of the invention, the elongate member of the knot-tying assembly is mounted for rotation on an axis perpendicular to the axis of rotation of the package.
According to yet another preferred embodiment of the invention, the elongate member comprises a hollow tube, and wherein the strand capture assembly includes a hook movable between a retracted position within the elongate member and an extended position in a strand capture position relative to the strand.
According to yet another preferred embodiment of the invention, the invention includes a stationary yarn package support for holding a package having a supply of textile yarn wound thereon with an exposed free end residing on an outer surface of the package and a stationary yarn gripper for releasably gripping and holding a length of the yarn adjacent the exposed free end of the yarn. A loop-forming swing arm is provided for forming a loop in the length of the yarn adjacent the exposed free end of the yarn and intermediate the gripper and the package. The loop-forming swing arm is mounted for rotation about an axis parallel to a longitudinal axis of the package in spaced-apart relation to the outer surface of the package and intermediate the surface of the package and the yarn gripper for separating a length of yarn from the surface of the package. The loop-forming swing arm includes thereon an elongate member mounted on the loop-forming swing arm for twisting the length of yarn separated from the surface of the package and held by the gripper about an axis perpendicular to the axis of rotation of the loop-forming swing arm for forming a secondary loop therein. A knot-forming assembly is carried by the elongate member for capturing a second length of the yarn separated from the surface of the package and pulling the second length of yarn through the secondary loop and thus forming a slip-knot in the loop of the strand formed by the loop-forming assembly adjacent the free end thereof. The slip-knot is adapted to be subsequently removed when desired by pulling on the free end of the strand.
According to yet another preferred embodiment of the invention, the invention includes a textile winder having a plurality of winding stations for winding yarn onto yarn packages and a conveyor assembly for conveying yarn packages from the winding stations to the knot-tying machine.
According to yet another preferred embodiment of the invention, the invention includes second conveyor assembly for conveying yarn packages with the slip-knot formed thereon to a remote location for packaging.
An embodiment of the method according to the invention of tying a knot in a strand carried on a package comprises the steps of mounting a package having a supply of a strand material with an exposed free end wound onto an outer surface of the package, gripping and holding a length of the strand adjacent the exposed free end of the strand, forming a loop in the length of the strand adjacent the exposed free end of the strand and intermediate the gripper and the package by relative rotational movement of the package and a loop-forming assembly, and forming a slip-knot in the loop of the strand formed in the strand of a type adapted to be subsequently removed when desired by pulling on the free end of the strand.
According to yet another preferred embodiment of the invention, the step of forming the loop comprises the step of rotating a loop-forming assembly about an axis of rotation of the package in spaced-part relation thereto for capturing and separating a length of the strand from the surface of the package.
According to yet another preferred embodiment of the invention, the method includes the steps of mounting a loop-forming assembly in stationary relation to the package, mounting the package for rotation about an axis which is stationary relative to the loop-forming assembly, providing a gripper mounted concentrically with the package support for rotation therewith, and rotating the knot-forming assembly relative to the loop formed by the loop-forming assembly for inserting the knot in the loop.
According to yet another preferred embodiment of the invention, the step of forming the loop includes the steps of moving an elongate member movable between a retracted position, an extended position within the loop formed by the loop-forming assembly, a secondary loop-forming position wherein the elongate member is mounted on a pivot for rotation to form a secondary loop in the loop, providing a strand capture assembly carried by the elongate member and capturing a length of the strand between the loop and the gripper and pulling the length of strand through the secondary loop to form the slip knot.
According to yet another preferred embodiment of the invention, the method includes the step of mounting the elongate member of the knot-tying assembly for rotation on an axis perpendicular to the axis of rotation of the package.
According to yet another preferred embodiment of the invention, the elongate member comprises a hollow tube with a hook carried therein and movable between a retracted position within the hollow tube and an extended position in a strand capture position relative to the strand.
According to yet another preferred embodiment of the invention, the method comprises the steps of holding in a stationary position a package having a supply of textile yarn wound thereon with an exposed free end residing on an outer surface of the package, releasably gripping and holding a length of the yarn adjacent the exposed free end of the yarn, forming a loop in the length of the yarn adjacent the exposed free end of the yarn and intermediate the gripper and the package by rotation of a loop-forming swing arm about an axis parallel to a longitudinal axis of the package in spaced-apart relation to the outer surface of the package and intermediate the surface of the package and the gripped yarn, separating a length of yarn from the surface of the package, twisting the length of yarn separated from the surface of the package about an axis perpendicular to the axis of rotation of the loop-forming swing arm for forming a secondary loop therein, and capturing a second length of the yarn separated from the surface of the package and pulling the second length of yarn through the secondary loop and thus forming a slip-knot in the loop of the strand formed by the loop-forming assembly adjacent the free end thereof, the slip-knot being adapted to be subsequently removed when desired by pulling on the free end of the strand.
According to yet another preferred embodiment of the invention, the method includes the step of rotating the package in the wind direction sufficiently to pull the secondary loop tightly around the length of yarn pulled through the secondary loop.